Have to disagree to some extent. If uke was allowed to change his grip in accordance to Tori's movement (this would be a stronger position for Uke because it evolves like in real life), then Uke wouldn't be able to do that technique at all. A strong position will constantly evolve. That's the basics of Aikido.

All these type of demos fall under the false pretense that Uke is going to be a static loaf. They do teach a basic principal but like you said it's blatantly obvious and totally one sided.

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Demos are demos
But since you decided to talk about real time applicability.....I am not changing one single comment or opinion. What I do in solo training, I do in kata, I do in drills, I do in sparring, I do in fighting. The only reason it looks different is due to speed, and the type of attacks someone brings. IP/aiki is not only fluid, it is hyper fluid and produces power and aiki non-stop in motion, and what SHioda is demonstrating can fit the bill if you know what you're doing.
To be fair, I have yet to see, feel, or meet an Aikido or Daito ryu person of any rank who both understands and can do, what I just said to you to the level I am talking about. I'm not saying they don't exist, I just have never seen it.
Cheers
Dan